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Mice in Offices

By Chris Williams on October 27, 2011.

Q. The office floor where I work has a mouse problem! We can’t figure out why. We’ve had a pest control company do some trapping and baiting, but we’ve still got mice. Any suggestions for other things we can do to get rid of the mice?

A. There are two primary reasons mice can become established in offices: available food and lots of clutter. You wouldn’t think that a room full of desks would be a likely place to find mice. But employees eat and drink at their desks. You might be hard-pressed to find a desk that doesn’t have a candy bar or bag of chips in a drawer. First, make sure your pest control contractor does a thorough inspection to find mouse nest sites and mouse runways, and then concentrates his control measures in these “hot spots.”

Mice usually establish their nests within 30 feet of a food source. They learn to search around employee desks, vending machines, kitchenettes, or in break rooms for spilled food. Chances are you will find them nesting near these sites as well under equipment or appliances, inside insulation, in stove pan drawers or desk drawers, in lower cabinets, and in any voids that are near food or water. Mouse runways are usually hidden within voids or along utility chases, in suspended floors or ceilings, or behind boxes or filing cabinets.

In an office building, a mouse infestation may be traced to a few offices of “clutterbug employees.” These are the offices that have boxes stored in every nook and cranny, many of which are never moved or opened—and which provide good mouse nest sites. Clutterbug offices also have files or drawers crammed full of papers. Mice can often be found nesting in the back corners of these drawers. If clutterbug offices also contain food, mice can be very happy there.

Other office locations where mice can be found nesting are: (1) vacant, unused desks of former employees, (2) custodial closets and utility closets with phone banks, (3) behind cabinet bases in kitchenettes or break rooms, (4) in undisturbed boxes, (5) in suspended ceilings and floors, (6) in wall voids, including inside modular cubicle dividers that are not capped, and (7) along heating system lines or pipe chases.

An interoffice campaign to discourage employees from storing food in their desks and to encourage them to clean up after themselves in the lunch room will go a long way towards resolving mouse problems. Involve custodial staff as well. Better cleanup of crumbs and spills, especially in those overlooked places like under vending machines and refrigerators, will help too.

Stored papers and records that aren’t essential should be recycled or shredded. Papers that need to be kept but aren’t used frequently should be stored elsewhere. Boxes of materials should be stored up off of the floor on racks or pallets. The racks or pallets should be 18 inches out from the walls to allow cleaning and inspection behind, and to make that space undesirable as a mouse runway.